No.
I'm kinda with the OP on this entire line of thought. The longer the MSQ goes (and it does look like all future MSQ will be stacked on top of what we have now), the less... I wanna lightly use the word "right" the game has to tell us "welp, after Xhundred hours, I guess you're just not good enough to unlock the whole MMO!"
This goes deeper than dungeons ("In from the cold" anyone?), this is a big problem with the idea of "MSQ as both gate to the game *AND* a skill test." It's busted, it's escalating, and the entire concept is audacious. There comes a point where you've proven yourself and should just... get to rely on unlocking the game because it would be ridiculous to get blocked at the 11th hour.
The dead ends is a part of the problem. Less so because yes, it's group content and you COULD get carried through it, (again, see "in from the cold") but it's still a problem. After Xhundred hours in the MSQ, I should not have to be Xhundred times better to just... unlock the game! Should I just expect that the day will come in another decade where, at a decade older, my reflexes won't be able to hack the MSQ? Am I just done then? In any other game it might be reasonable, but not in an MMORPG like this.
Just my opinion.